THE  UNIVERSITY 


OF  ILLINOIS 
LIBRARY 


/ 92S 
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UNIVERSITY  OF  ILLINOIS 


___JIAZ_2.5 i922__. 


THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 


L MQ2EER  _ LdlUlZilEUIER . 


ENTITLED ^--STIII)Y_Oi!_^UlLniE-TK_OjTIS._AlIIL_aEAHaOAL. 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
DEGREE  OF  BAGHSLQH..CL5_^GLSl!lGE 


: -r  O V 

S y/W  i'  4i 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/studyofsulfurincOOmont 


This  work  was  undertaken  at  the  suggestion  of 
Dr*  li!.  J.  Bradley  and  carried  out  under  his  direction. 
The  7/riter  wishes  to  take  this  opportunity  to  ex- 
press his  appreciation  and  thankfulness  to  Dr*  Bradley 
for  his  guidance,  suggestions,  and  helpful  criticisms, 
and  to  B.W,  Weeterman  and  F.3*  Yanderveer  for  their 
help  in  the  experimental  work  of  this  investigation. 


TABLE  OF  COUTEiTTS 


Page 

I.  Introduction  1 

II.  Literature  7 

A.  Bulphur  in  Coal  7 

B.  Clianges  in  the  sulphur  Combinations  8 
During  the  Coking  Process. 

C.  Sulphur  in  Coke  10 

D.  Possible  Character  of  Sulphur  Compounds 

in  Coke  and  Charcoal.  14 

III.  Experimental  18 

A.  Description  of  Apparatus  is 

3.  Method  of  Operation  19 

C.  Method  of  Analyzing  Products  ly 

D.  Preliminary  Work  20 

E.  Series  of  Experiments  Using  CSg  22 

F.  Series  of  Experiments  Using  EgS  26 

Go  Series  of  Experiments  Using  Eg  29 

H.  Removal  of  Sulphur  by  Steam  and  Water  Gas  50 

I,  Removal  of  sulphur  by  Miscellaneous  Gases  32 

IV.  summary  34 

V.  Bibliography  36 


-1- 


A Study  of  sulphur  in  Coke  and  Charcoal 
I.  Introduction 

A. 

It  is  the  purpose  of  the  investigation  to  study  the 
forms  of  sulphur  in  coke  and  charcoal  and  their  reactions  at 
different  temperatures  toward  various  vapors  and  gases  to  give 
additional  information  which  may  apply  to  the  removal  of  sulphur 
from  metallurgical  coke  and  gas,  Wood  charcoal,  and  petro- 
leum, metallurgical,  and  low- temperature  coke  were  heated  at 
various  temperatures  and  subjected  to  EgS  and  CSg  vapors. 

Surface  and  interior  samples  were  taken  of  the  resulting  carbon 
substances.  This  impregnated  coke  or  charcoal  was  then  returm- 
ed  to  the  furnace  for  further  treatment  to  determine  the  effect 
of  various  gases,  as  hydrogen,  superheated  steam,  water  gas, 
xylene,  and  illuminating  gas  in  removing  the  sulphur  from  the 
coke  and  charcoal.  All  outgoing  gases  were  analyzed  before 
burning. 

B. 

Sulphur  has  always  been  an  unwelcome  constituent  of 
coke  and  gas  and  as  the  supply  of  low  sulphur  coal  constantly 
decreases  th^resence  of  more  and  more  sulphur  in  these  becomes 
a problem  of  great  industrial  importance.  This  high  sulphur 
coke, when  used  in  making  iron  and  steel,  produces  a poor  grade 
of  metal,  making  it  brittle^  and  more  easily  attacked  by  acids^* 
As  a fuel,  not  only  does  sulphur  lower  the  heating  value,  but 
also  increases  the  difficulties  of  operating  the  boilers  and 


and  disposing  of  waste  products,  and  causes  corrosion  of  metal 
parts  such  as  valves,  boilers  and  chimneys,  and  even  concrete 
structures^*  In  gas  it  produces  unpleasant  fumes,  corrodes 
chimneys  and  metal  parts  of  lamps,  burners,  roofs,  guy  ropes, 
etc.  Gas  purification  has  also  now  become  a problem  of  consid- 
erable importance  from  a chemical  and  industrial  point  of  view. 
The  use  of  gas  in  chemical  industries  has  recently  been  devel- 
oped. The  generation  of  hydrogen  for  the  requirements  of  cat- 
alytic hydrogenation  processes  calls  for  the  purification  of 
enormous  volumes  of  water  gas*  This  reqtlAres  au  extremely  oare- 
■ ®liniination  of  all  sulphur  compounds,  as  otherwise  the  mach- 
inery would  soon  be  ruined,  the  steel  would  soon  deteriorate  in 
strength,  and  the  catalysts  be  poisoned^^  Again,  the  sulphur  in 
producer  gas  is  a big  disadvantage  to  steel  manufacturers  since 
open  hearth  steel  is  contaminated  by  this  element^. 

The  above  enumeration  of  some  of  the  most  deleterious 
effects  of  sulphur  in  coke  and  gases,  along  with  the  fact  that 
every  day  our  supply  of  coals  of  low  total  sulphur,  the  most  im- 
portant factor  affecting  the  sulphur  content  of  the  coke  and  gas, 
are  rapidly  diminishing,  indicate  the  importance  and  necessity 
of  directing  more  and  more  attention  to  this  problem. 

C. 

All  the  known  processes  used  to  produce  a low  sulphur 
coke  may  be  divided  into  three  classes: 

(1)  Those  processes  in  which  an  attempt  is  made  to  re- 
move the  sulphur  from  the  coal  before  coking. 

(2)  Those  processes  which  involve  the  elimination  of 


-3- 


the  sulphur  as  volatile  compounds  or  its  conversion  into  such 
compounds  at  the  temperature  of  the  coking  process,  which  may 
later  be  leached  out  with  water, 

(3)  Those  processes  in  which  the  sulphur  of  the  finished 

g 

coke  is  attacked  to  secure  its  removal 

Under  the  first  method  we  have  attempts  to  eliminate  the 
sulphur  from  the  coal  by  washing  it.  The  success  of  this  meth- 
od depends  upon  the  form  in  which  the  sulphur  occurrs,  and  upon 
the  efficiency  of  the  washer  . This  treatment  removes  a part 
of  the  sulphur  which  is  combined  as  pyrites,  but  affects  neither 
the  finely  disseminated  iron  pyrites  nor  the  sulphur  in  organic 

7 

combination  o In  most  cases  one  fourth  to  one  half  of  the  sul- 
phur of  the  coal  can  be  removed  bj?-  washing,  which  means  a cor- 

8 Q 

responding  reduction  in  the  coke  sulphur  . J.E.  Campbell  ad- 
vocates the  sink  and  float  method  for  washing  coals,  which  he 
says  will  reduce  the  sulphur  content  E6-40fb# 

The  second  method  is  probably  by  far  the  most  common  one 
for  it  is  more  convenient  to  apply  a desulphurization  process 
during  the  carbonization  period  than  to  the  finished  coke. 

F.  Wuest  and  P.  Wolff^®  state  that  the  practice  of  coking  coals 
owed  its  origin  not  so  much  to  the  desire  of  obtaining  a non- 
flaming fuel  as  to  the  idea  that  the  all  important  object  to  be 
obtained  was  the  desulphurization  of  the  coal,  A successful 
process  must  of  necessity  be  cheap,  and  m.ust  remove  a large 
percentage  of  sulphur,  and  must  not  affect  the  quality  or  quan- 
tity of  the  coke  produced.  Among  the  methods  of  this  group 
we  have  the  processes  involving  the  passage  of  gases  through  the 


-4- 


ooking  mass,  A.  Soheerer^^  claimed  a loss  of|o.4f!.  sulphur  was 
produced  by  passing  high  pressure  steam  through  the  oven  before 
drawing  the  coke,  A patent  of  Claridge  and  Boper  in  1858  invol- 
ves  the  same  process.  Woltereck  combined  air  and  steam  at  not 
over  400 °C.  The  sulphur  was  driven  out  as  SOg  but  excessive 
amounts  of  coke  were  used  to  obtain  the  desulphurization.  Wuest 
and  Wolff^^  in  experimenting  on  the  passage  of  various  gases  over 
powdered  coke  removed  by  steam  12.84ft'  of  the  sulphur  of  the  coke 
at  500^0 , 36. 8&^  at  800^0 , and  54.34ft  at  lOOOOc.  From  the  excess- 
ive loss  of  coke  by  ignition  as  compared  to  the  desulphurization 
produced,  they  concluded  that  such  a procedure  was  not  practicable. 
With  nitrogen  they  found  that  2,41ft  of  the  sulphur  of  the  coal 
was  removed  at  500°C,  6.97ft  at  900°C,  and  17.35ft  at  lOOOOc.  With 
COg  6.47ft  v/as  volatilised  at  500®C  increasing  to  59.24^  at  lOOOOc, 
but  a very  great  ignition  of  the  coke  resulted.  They  assumed  the 
reaction  200£  + 8*^  200  *f  SOg  to  take  place,  the  burning  of  the 
sulphur  to  sOg  depending  on  the  reduction  of  COg  at  high  tempera- 
tures by  contact  with  carbon.  Phillipart^^  eliminated  part  of  the 
sulphur  in  coke  as  20g  by  passing  air  through  the  coking  mass,  but 
only  at  the  expense  of  large  quantities  of  coke.  There  are  two 
processes  involving  the  use  of  chlorine  gas.  E.L.  Stonerl3  treat- 
ed the  coke  in  the  retort  at  the  end  of  the  coking  operation 
with  hot  chlorine  or  chlorinated  gases,  and  then  washed  to  remove 
soluble  salts.  The  process  is  expensive  and  tends  to  destroy  the 
character  of  the  coke,  and  its  byproducts.  Fingerland,  Indra, 
and  Ilesnerl^  claimed  to  produce  a low  sulphur  coke  by  distrib- 
uting catalysts  as  metals,  or  the  hydroxides,  oxides,  or  salts 


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of  iron  in  the  coke  "before  coking,  and  during  cr-rhonization 
passing  chlorine  vapor  through  the  hot  coke,  The^  held  that  the 
resulting  compounds,  Fe^clg  and  SClg,  volatilized  in  the  current 
of  chlorine  so  that  the  ash  content  of  the  coke  vas  not  increased. 
They  also  claimed  that  at  the  same  time  portions  of  the  hydrogen 
contained  in  the  coke  escaped  as  HCl,  enriching  the  residue  in 
carbon.  The  excess  chlorine  was  removed  by  bloving  steam,  hydro- 
gen, or  gases  containing  hydrogen  through  the  incandescent  coke. 
Severe!  patents  on  the  use  of  00  in  desulphurizing  have  been  re- 
corded but  they  give  no  data  as  to  their  efficiency.^  Wuest  and 
TTolff  however,  found  12*8f^  of  the  sulphur  of  the  coal  or  coke 
removed  at  500°C  by  CO,  the  percentage  increasing  to  at 

lOOO^C  with  a comparatively  low  ignition  loss.  They  considered 
the  reaction  to  be  S f SCO  “ 2C  SOg.  ?/ith  hydrogen  they  found 
7*59^  volatilized  to  H£S  at  6C0°C  increasing  to  22,09f^  at  600°C 
and  51. 17^  at  1000°C;  extending  the  time  of  treatment  in  every 
osse  increased  the  removal,  since  they  were  unable  to  ascertain 
the  exact  nature  of  the  organic  sulphur  present  in  the  coke,  they 
explained  the  results  from  the  reaction  FeS  + 2E  “ 2Fe  <►  H^S. 

A.B.  Powell®  oonduoted  experinents  to  stud-  the  removal  of  sul- 
phur hy  using  hydrogen  gas,  either  pure  or  as  contained  in  hy- 
produot  gas.  Pure  hydrogen  was  first  passed  thjrough  a small  Ish- 
oratory  apparatus  at  the  end  of  the  coking  operation,  at  the 
rate  of  lOOoo  per  minute  at  the  temperatures  up  to  lOCOOc.  The 
entire  desulphurization  effect  of  the  hydrogen  was  found  to 
be  due  to  the  increased  conversion  of  the  organic  sulphur  to  H s. 
_elow  600  C the  elimination  of  the  sulphur  due  to  the  hydrogen" 


-6- 


is  very  slight  hut  above  500 °C  it  is  increased  enormously,  as 
high  as  90fo  in  a Freeport  coal  studied,  showing  that  desulphur- 
ization in  this  coal  is  most  active  at  the  higher  temperatures 
of  the  coking  process.  Powell  further  states  that  a secondary 
reaction,  due  to  a mass  action  effect,  fixes  the  sulphide  sul- 
phur in  some  combination  with  the  carbon  of  the  coke,  the  hydro- 
gen causing  an  increased  decomposition  of  the  pyrite  up  to  500°C 
and  the  constant  elimination  of  the  organic  sulphur  above  that 
temperature  as  HgS.  A bOfc  mixture  of  hydrogen,  as  in  by  product 
gas,  produced  much  slower  desulphurization,  but  caused  a decided 
removal  of  the  sulphur. 

There  are  also  those  processes  involving  the  addition  of 
compounds  before  coking.  In  the  Calvert^^  process  in  England 
salt  is  added  v/hich  is  said  to  give  good  results  by  forming,  dur- 
ing the  coking  period,  volatile  compounds  of  sulphur.  It  has 
never  been  applied  on  a commercial  scale  however.  Franck^^  has 
a patent  process  involving  the  addition  of  hnOg  which  he  claims 
liberates  oxygen  and  effects  a rapid  combustion  of  the  organic 
sulphur  compounds. 

The  quenching  operation  may  be  considered  a process  of 
desulphurif«ation  of  the  third  class  in  which  the  removal  of  the 
sulphur  of  the  finished  coke  is  attempted.  J.B.  Campbell^^ 
states  that  the  action  of  the  water  in  quenching  reacts  on  the 
iron  sulphide  of  the  coke, as  follows;  FeS  4*  E2O  = FeO  + H£S. 
Experiments,  however,  show  that  only  an  infinitesimal  percentage 
of  sulphur  is  evolved  during  the  process.  It  is  stated  that  the 
addition  of  ECl  to  the  water  will  greatly  facilitate  the  removal 
of  the  sulphur.  Eoffinan^^  states  that  the  addition  of  an  acid 


-7- 

solution  of  manganic  and  calcinm  chlorides  to  coke  removes  sul- 
phur as  EoS.  As  has  "been  already  stated  it  is  more  convenient 
to  apply  the  necessary  desulphurization  process  during  the  car- 
bonization period  than  before  or  afterward.  As  Powell^  states, 

" if  in  some  way  one  might  affect  the  sulpur  reactions  of  the 
coking  process  so  as  to  secure  larger  amounts  of  the  volatile 
sulphur  compounds  and  less  of  the  residual,  the  problem  would  be 
greatly  simplified”.  It  is  quite  possible  that  the  lean  gases, 
byproducts  of  the  carbonization  of  coal,  might  be  utilized  for 
the  desulphurization;  such  a process  would  not  injure  the  coke 
and  not  materially  affect  the  byproduct  gas  itself. 

A successful  application  of  this  however  requires  an  exten- 
sive knowledge  of  the  reactions  which  the  sulphur  undergoes  during 
the  coking  and  the  nature  of  its  combination  and  occurrence  in 
the  coke. 

II.  Literature 

A. 

It  is  now  quite  generally  conceded  that  sulphur  occurs  in 
coals  in  an  inorganic  form,  mixed  mechanically  with  the  coal, and 
as  resinic  and  humic  constituents  in  organic  form^®.  Pyrite  is 
generally  found  in  coal  as  well  as  marcasite  and  magnetic  pyrite, 
Fe^Sg.  Other  inorganic  compounds  also  occur  rarely,  as  in  sul- 
phates,  but  the  amount  ie  generally  small  . It  was  formerly  be- 
lieved that  all  the  sulphur  in  coal  was  present  as  pyrite,  FeS£, 

but  this  is  now  known  not  to  be  true. 

20 

In  1843  Berzelius  apparently  made  first  mention  of  a solid 
organic  compound  of  sulphur  in  coal  when  he  stated,  ”Lie  Kohle 


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enthSlt  Scliwefel  in  chemischer  Verbindting  der  nicht  dnrch  Glllhen 
ausgetrieben  warden  kann,  wenn  dabei  der  Zutritt  der  luft  verhin- 
dert  wird’’.  Professor  J.G.  Wormley^^  (1673)  called  attention  to 
the  fact  that  many  coals  containing  little  iron,  have  a larger 
percentage  of  sulphur  than  can  be  accounted  for  if  the  sulphur  were 
combined  only  with  the  iron  found  in  the  coal.  His  experiments 
go  to  prove  that  a large  part  of  the  sulphur  found  in  coals  exists 
as  some  organic  compound,  the  exact  nature  of  which  he  was  unable 
to  determine,  A,S,  M'Creath^S  drew  the  same  conclusion,  reasoning 
from  the  excess  of  sulphur  required  to  convert  the  iron  into  iron 
pyrite,  Himball^S  reviewed  the  whole  field  of  sulphur  in  coal  and 
concluded  that  some  of  it  may  be  combined  with  organic  matter,  the 
same  as  it  is  supposed  to  be  combined  with  rubber  in  vulcanized 
rubber,  Prown^^  observed  figures  from  his  analyses  which  lead  him 
to  believe  that  sulphur  must  exist  to  a great  extent  in  coal  as 
organic  sulphur,  Wuest  and  TTolfflO  point  out  from  the  analyses  of 
Muok^*"and  3lum26  that  percentages  of  organic  sulphur  in  coal,  ex- 
pressed in  percentages  of  the  total  sulphur  content,  vary  from 
66-r92f4,  Wheeler  showed  by  extracting  coals  with  CHCI-7  and 

that  organic  sulphur  is  present.  Thiessen^*^  from  a micro- 
soopio  examination  of  coal  in  thin  sections,  states  that  a certain 
amount  of  sulphur  is  found, to  be  present  in  an  amicroscopic  form 
probably  to  be  recognized  as  organic  sulphur. 

3. 

When  coal  is  subjected  to  destructive  distillation  in  the 
absence  of  air  the  sulphur  divides  between  the  residue  and  the  vol- 
atile matter.  The  phenomena  taking  place  during  this  transforms- 
tion  of  coal  to  coke  is  quite  complicated  and  it  is  difficult  to 


-9- 


determine  in  what  relation  the  sulphur  of  the  coal  is  divided  be- 
tween the  organic  and  inorganic  conipounde  end  whether  the  sulphur 
as  PeSr,  or  in  the  organic  form  is  the  more  volatile,  Drovm®8 
found  that  in  coals  containing  a considerable  amount  of  sulphur 
both  as  metallic  sulphide  e,nd  as  e,n  inherent  constituent  of  the 
coal,  and  at  the  same  time  low  in  volatile  matter,  the  elimination 
of  the  sulphur  during  the  coking,  appeared  to  be  limited  to  a 
portion  of  that  existing  as  pyrites,  the  organic  sulphur  not  be- 
ing affected,  by  the  process.  In  other  coals, lowr  in  pyrites,  and 
low'er  in  volatile  matters  there  was  an  elimination  of  organic 
sulxh.ur  to  the  extent  of  25-45f:.  Widely  divergent  results  and 
many  different  theories  have  been  advanced  to  explain  the  reac- 

20J 

tions  undergone  by  the  coal  sulphur  during  this  change.  McCallum 
concluded  that  a somewhat  greater  percentage  of  the  organic  sul- 
phur than  of  the^rganic  was  volatilized.  J.S.  Campbell^^  states 
that  most  of  the  coal  sulphur  is  pyritic,  thtt  42^"'  of  this  is 
volatilized  during  the  coking  process,  the  rest  remaining  in  the 
coke  as  pyrrhotite  and  that  most  of  the  organic  sulphur  is  re- 
tained in  the  coke.  .erofessor  S.V7.  x-arr^^  states  tha.t  in  the 
coking  process,  the  organic  sulphur  in  the  coal  is  broken  down, 
part  of  it  remaining  in  the  tar  oils  as  thiophenes,  end  part  going 
with  the  fixed  gases  as  IlgS,  and  half  of  the  sulphur  of  the  FeSg 
is  discharged  for  the  most  part  below  500°C»  As  700°C  is  approach  - 
ed  the  final  sulphur  of  FeS  is  discharged  leaving, metallic  iron 
and  a carbon  suphur  compound.  Powell  in  a lengthy  discussion 
of  the  reactions  taking  place  during  the  carbonization  period 
states  that  a decomposition  of  the  pyrite  occurs  at  300°C,  is 
complete  at  600°C,  and  reaches  its  maximum  between  400g500*^C* 


-10- 


Also  that  it  may  be  assumed  that  any  sulphates  present  v/ill  he 
reduced  to  the  suj)hide.  In  the  presence  of  a large  excess  of 
the  coal  substance  the  decomposition  of  the  pyrite  produces  FeS 
and  A large  part  of  the  former  is  further  decomposed, 

the  sulphur  apparently  entering  into  combination  with  the  carbon. 
The  evidence  for  this  is  simply  the  fact  that  during  .the  later- 
stages  of  the  coking  process  there  is  quite  a decided  increase 
in  the  sulphur  held  in  the  carbon- sulphur  combination,  with  a 
decrease  in  the  amount  of  sulphides  present.  He  also  states 
that  the  organic  sulphur  of  the  coal  persists  almost  unchanged 
in  type  up  to  400^0 . From  400^0  to  £00°C  a decided  change  in 
its  charscter  takes  place  but  the  resultant  carbon- sulphur 
combination  has  all  the  properties  of  the  sulphur,  existing  in 
this  form  in  t he  finished  coke.  Secondary  reactions  also  play 
an  extremely  important  part  in  the  coking  process,  those  between 
the  organic  sulphur  compound  and  the  hydrogen  of  the  gas  to  form 
HgS  and  the  red  hot  coke  to  form  CSg  being  typical.  The  fact 
that  the  latter  substance  is  not  a primary  product  of  coal  dis- 
tillation has  long  been  known. 

C. 

After  tracing  the  changes  which  the  sulphur  of  the  coal 
undergoes  during  the  coking  process,  we  naturally  find  ourselves 
asking  as  to  the  nature  of  this  sulphur  retained  in  the  coke 
This  has  always  been  a problem  difficult  to  solve.  Powell^ 
states  that  it  consists  of  iron  sulphide  either  as  FeSg  or  pyr- 
rhotite  along  with  a larger  quantity  of  a very  stable  organic 
substance.  This  latter  form  is  not  affected  by  either  HCl  or 
HllOg  and  is  extremely  stable  to  the  action  of  oxidizing  agents 


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11- 


and  heat  at  1000*^0,  but  is  readily  discharged  from  combination 
by  the  action  of  nsscent  hydrogen^^.  V/.A.  Bradbiiry^^  as  early 
as  1878  states  that  the  data  of  Percy^^  gives  analytical  evi- 
dence to  support  the  statement  that  sulphur  is  presnt  in  coke 
in  some  organic  combination,  and  may  be  considerably  more  than 
intthe  form  of  sulphide.  Truest  and  Wolff^^  found  the  propor- 
tion of  organic  sulphur  in  coal  as  8d*2^  of  the  total  sulphur 
present. 

Just  what  is  the  form  of  this  organic  sulphur  compound 
of  coke?  Solid  compounds  of  carbon  and  sulphur  formulated  as 
CS,  C2S3,  and  0285  have  been  described  but  these  are  either 
gaseous,  liquid  or  if  solid  have  melting  points  far  below  the 
temperature  of  coking  • Since  it  seemed  impossible  to  isolate 
the  compound  from  coke  many  investigators  have  applied  a syn- 
thetic method  of  attack  in  an  endeavor  to  throw  more  light  on 
the  problem.  In  1865  John.  Hunter^"^  experimented  v/ith  the  pas- 
sage of  CS2  over  cocoanut  charcoal,  and  obtained  the  following 
data: 

(1)  117.7  vol.  of  CS2  absorbed  at  100°C  at  pressures  varying 
from  671.0  to  671.2  mm.  (2)  91.2  vol.  of  CSg  absorbed  at  167.1 
to  168. 4°C  at  pressures  varying  from  658.1  to  658.6mm.  (3)  81.7 
vol.  of  OS2  absorbed  at  101.7O  to  191.3°C  at  pressures  varying 
ffom  690*3  to  564.4  mm.  (4)  88.5  vol.  of  CS2  absorbed  at  160*3 

to  162*8°C  at  pressures  varying  from  697.9  to  679.0  mm, 
from  a,  mixture  of  lOcc  of  CSg  and  20cc  of  alcohol. 

Calculating  this  to  the  percent  sulphur  found  in  the 
charcoal  we  find  17.75^  retained  in  (1),  12*45f^  in  (2),  11.19^ 


-12- 


in  (3)  and  12.59f^  in  (4).  It  is  to  le  noted  that  with  the  ex- 
ception of  (4),  decreasing  amomits  of  sulphur  are  retained  v^'ith 
increasing  temperatures.  W.G.  Mixter^^  (1693)  found  that  when 
sulphur  vapor  was  passed  over  soft  sugar  carhon,  and  the  latter 
then  cooled  and  dried  with  a stream  of  hydrogen,  the  carbon  was 
found  to  have  retained|l9.97f^'  sulphur.  Y/hen  subjected  to  the 
heat  of  the  combustion  furnace,  it  gave  off  a little  KgS  but  no 
CS? , and  when  heated  in  s Perrot  furnace  at  a temperature  suf- 
ficient  to  melt  cast  iron  readily,  the  carbon  still  retained  3.4^ 
of  sulphur.  However  when  the  sugar  carbon  v;as  first  heated  to 
the  highest  temperature  of  the  combustion  furnace  to  drive  out 
all  occluded  gases  and  then  subjected  to  sulphur  vapor  for  twenty 
minutes  and  cooled  and  dried  with  hydrogen,  no  sulphur  combined. 
When  GS^  was  passed  over  the  charcoal  at  a red  heat  and  exposed 
to  the  sulphur  vapors,  and  then  cooled  as  in  the  other  experi- 
ments 11*14^  of  sulphur  was  retained.  Filter  paper  charred  at 
a dull  red  heat,  and  exposed  to  sulphur  vapors  showed  a retention 
of  29*1^  S.  Loose  rolls  of  filter  paper  soaked  with  a saturated 
solution  of  S in  0S£,  gradually  heated  to  incipient  redness, 
dried  and  cooled  with  hydrogen,  retained  about  46 sulphur. 

This  resulting  charcoal  yielded  nothing  to  boiling  CSg  and  gave 
up  no  sulphur  to  a boiling  HOE  solution.  He  concluded  that  his 
results  show  that  nearly  pure  amorphous  carbon  takes  up  little 
sulphur,  while  a soft  charcoal,  containing  hydrogen  and  oxj.’-gen, 
takes  up  considerable  sulphur  from  and  forms  a chemically 
combined  compound  not  removed  by  solvents  even  when  it  contains 
nearly  50f^  of  sulphur,  but  is  entirely  removed  by  hydrogen 
under  proper  control.  Wibaut  and  Stoffel  ^^,h€afAn^  sugar 


-13 


carlaon  or  wood  charcoal  mixed  with  sulphur,  in  a closed  crucible 
to  a bright  red  incandescence  obtained  products  which  after  ex- 
traction with  OSg  and  then  ether,  contained  sulphur  to  the  ex- 
tent of  3-6f!',  They  were  unable  to  decide,  hov/ever,  whether  it 
was  chemically  combined  or  only  absorbed.  Jeude  in  study- 

ing compounds  of  sulphur  with  carbon,  stable  at  high  temperatures 
drew  the  follov/ing  conclusions  from  his  work: 

fl)  Carbon  seems  to  have  an  avidity  for  sulphur  at  high 
temperatures. 

(2)  A certain  percentage  of  the  sulphur  is  combined  with 
the  carbon  in  such  a v;ay  as  to  resist  the  action  of  solvents  on 
heating  in  a current  of  inert  gas  as  distinct  from  the  excess 
sulphur  which  is  removed  by  the  treatment. 

f3)  The  amount  of  the  sulphur  taken  up  by  the  carbon 
seems  to  depend  on  the  refluxing  temperature,  less  sulphur  being 
absorbed  at  the  higher  temperatures. 


(4)  The  loss  of  sulphur  when  heated  in  a stream  of  nitro- 
gen, seems  to  increase  with  increase  of  temperature. 

(6)  Cokes  made  at  high  temperature  are  relatively  stable 


at  low  temperature  when  heated  in  a stream  of  nitrogen. 


O.C.  Russell  , from  his  work  on  sulphur  in  coke,  under 
the  direction  of  Professor  Parr , concluded: 

(1)  In  the  study  of  absorption  of  sulphur  by  carbon, 
the  determination  of  volume  change  of  HgS  in  passing  over  heated 
carbon,  cannot  be  used. 

(2)  The  sulphur  of  KgR  is  ehsorhed  by  oe.rbon  In  increas- 
ing amounts  up  to  a temperature  of  700°  to  800°C,  but  above  this 


temperature  little  is  effected , the  infereno 


e being  that 


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'f{,'  .»  * T.  jk 


-14- 


hydrogen  formed  by  dissociation  of  the  HgS  begins  a purging 
action  at  this  point. 

fS)  Coke  carbon  begins  to  absorb  sulphur  above  450^0. 

f4)  FeS£  mixed  ?/ith  sugar  carbon  and  heated  to  750°C 

is  converted  into  a magnetic  sulphide  which  in  turn  is  partially 
reduced  to  metallic  iron. 

(5)  Carbon  absorbs  some  of  the  sulphur  which  is  liberated 
from  the  FeS  to  the  magnetic  sulphide. 

D. 

I • 

We  now  arrive  at  the  work  of  E.M.  Chiles  who  in  his 
studies  of  the  nature  of  nitrogen  compounds  in  coke,  was  apparent- 
ly the  first  to  call  attention  to  the  possible  explanation  of  the 
form  in  which  nitrogen  and  sulphur  occur  in  coke  by  Langmuir's 
theory  of  surface  compounds^^.  According  to  this  tbieory^f  we 
consider  s particle  of  pure  carbon,  each  atom  of  this  particle 
is  chemically  combined  to  all  the  adjacent  atoms,  v/hile  these  in 
; turn  are  combined  to  those  beyond.  The  arrangement  of  the  atoms 
in  general  does  not  follow  the  usual  rules  of  valence,  but  each 
atom  is  combined  with  a much  larger  number  of  atoms  than  cor- 
responds to  its  normal  valence.  Thus  the  valences  on  the  inter- 
j ior  carbon  atoms  may  be  considered  to  be  completely  saturated 
but  the  surface  layer  of  the  carbon  atoms  should  be  unsaturated 
and  quite  reactive,  combining  with  atoms  of  other  elements  much 
^ more  freely  than  can  the  atoms  of  the  interior.  The  surface  must 
be  looked  upon  as  a sort  of  a checkerboard  containing  a definite 
numoer  of  atoms  of  definite  kinds  arranged  in  a plane  lattice 
formation.  The  space  between  and  immediately  abovefsway  from  the 
interiorHhese  atoms  is  surrounded  by  a field  of  electromotive 


-15- 


force,  more  intense  then  that  "between  the  atoms  inside.  When  a 
molecule  strikes  against  the  solid  surface  it  may  "be  reflected, 
that  is,  rebound  elastically,  or  it  may  condense  on  the  surface, 
that  is,  it  may  "be  held  "by  the  attractive  forces  in  such  a way  , 
that  it  forms,  at  least  temporarily,  a part  of  the  solid  body. 

If  any  molecules  impinging  upon  the  surface  are  condensed  a cer- 
tain time  interval  must  elapse  before  they  can  evaporate.  This 
time  lag  will  bring  about  the  accumulation  of  molecules  in  the 
surface  layer  end  may  thus  be  looked  upon  as  the  cause  of  ad- 
sorption. Much  experimental  evidence  seems  to  show  that  this 
is  a truly  chemical  phenomenon.  Chiles  states  that  in  the  cok- 
ing process  we  have  the  phenomenon  of  decomposition  of  compounds 
of  the  original  coal  with  the  production  of  carbon  and  the  fur- 
ther decomposition,  in  contact  with  the  carbon,  of  the  hydro- 
carbons, sulphur  compound,  nitrogen  compounds,  etc*,  probably 
with  the  production  of  elementary  hydrogen,  sulphur,  nitrogen, 
etc.  One  might  assume  that  the  original  carbon  particles 
would  become  saturated  with  the  elements  produced  in  the  atomic 
state  in  contact  with  the  carbon. 

To  get  a clearer  idea  of  the  carbon- sulphur  combination 
it  may  be  best  to  first  describe  a similar  compound  of  oxygen 
with  carbon  of  which  much  is  already  known,  and  then  point  out 
the  resemblance  of  the  corresponding  sulphur-  carbon  compound. 

It  is  to  be  noted  that  sulphur  appears  imraediately  below  oxygen 
in  the  periodic  table  and  has  many  properties  similar  to  oxygen, 

different  only  in  degree  and  not  in  kind. 

41 

In  1905,  E.E.  Armstrong  observed  results  causing  him  to 
conclude  that  the  simple  oxides  of  carbon,  CO  and  COg,  were  ob- 


01 


©ni-as  anQ.  ht  sq.o^3  Jn-ctdins  aiq-cssodmi  q.B  q.ou  si  q.i 

q.uara^ITj  aqq.  jo  i?poq 
Jiai^ei  naSi?xo 

0 0 0 

raainrajoj  aqq.  oq.  SxxxpjioooB  sq.ueraBiTj:  aqq.  jo  ifpoq  eqq  Suiiiijoj 
STnoq.ii  xioqjci30  aqq.  oq  saouax'SA  AjieinTjd  qqx-A  patziqraoo  ^xx'tjoxniaqo 
sraoq.«  naSiCxo  3.0  sqsxsnoo  q.i  ‘panuicj  sx  uaSifxo  paqxosp^  jo  mipj 
aiqsq.3  Axsa  ^ q.8qq.  tiaS^xo  tzx  sq.uaaieiTj  xcoqjHO  qqxis/i  sqnampjiadxa 
3xq  iJq  eAOJd  oq  shixbxo  •X'eoojCBqo  aqq  ^0  qqSxaM  X'STQ-Tnx 

^g^*2  oq  ^XA*I  raojj  saxdtn'as  o/Aq  nx  pexj-BA  X'Qoojcaqo  qqxM 
pauqqnioo  ao^  oq  pimoj  snqq  ne3i?xo  jo  qiniome  aqx  •iroq.ji^o  jo  anpx 
39j:  -8  SnxABax  ^xcfeiimsaxd  pixe  OO  ^OG  SxcxaxS  iix^ops  xi/Aop  X8aa:q 
naqq  sapxxo  asaqq  q^qq  Moqs  aq^p  jcxaqx  'paqo^aj:  sx  OqOOS  JO 
> JTi q-ej a dmaq  -e  XTO-tm  acyp^  Siixq^q  qou  sxqq  ‘noxqxsodmooap  jc  aq^j 
/Aox  i?o:aA  8 aA8q  qsaap  q8  j:o  saj-nq^jcadinaq  /^73xrxpjc  q8  axq-sqs  aq 
i sapxxo  asaqx  *qu:8qsxioo  ^XTJ^'^ssaoen  qoTi  sq  oq  tioqx80  jo 

);q8j:  aqq  qoxqM  nx  qnq  ‘sqnaqnoo  uaS^c  nx  ;aox  pun  noqjso  nx  qSxq 
iqjgo  JO  0apxxo  pxpos  ‘ajojanaqq  ‘aq  pxnoM  ifaqj;  •spnnodraoo  eo8j 
ia  S8  X'^oo-ieqo  aqq  i?q  ppaq  sx  naSiCxo  n'gsxrjii  sxqq  qsqq  pns  ‘noxq 
ijosqn  /q  nsqq  naqqo  x^oojnqo  ifquPaxxj,*  aq  u-&o  naSiCxo  qsqq  aptipo 
*y*G  pti8  *II*H  'qnasojcl  xapdiuoo  jo  qnnomn  aqq 


ssax  aqq  ajnqsnadniaq  aqq  jcaqSqq  aqq  q^qq  aqsoqpnx'  sqxxisajc  jcxaqj; 

/> 

•lO  pns  oQ^  oqnx  qsaq  ^?q  pesodTnooap  sx  qoxqA;  noxqxsodmoo  axqBXJCSA 

X 

i JO  0 0 xaxdnioo  uIBOxuiaqo-coxsiCqcI*,8  rajoj  oq  ^x4-Ooj:tp  noqjno  jo 
jsnm  8 qqxM  sanqqnioo  naSko  qaqq  noxsxixonoo  aqq  oq  pnax  iapaaqjii 
pnn  pnaqq  jo  saqojcgasaa  naqsp  eqi  ‘xapdraDO  naSi^xo  -ncqjso  pa 
ipqxo  i^xo^oi^Iraoo  ssax  JO  ajcoin  8 jo  xcMopq8aj[q  aqq  ^q  ^x^o  panxsq 

-91- 


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• Lv  q-  ■nr 


-17- 


way  as  oxygen  tmd  that  it  also  forms  with  coke  and  charcoal  this 
same  kind  of  surface  compound  in  which  the  sulphur  atom  is  in 
the  position  of  the  oxygen  in  the  formula  given.  We  could  then 
say  that  sulphur  comoines  with  a mass  of  carbon  directly  to  form 
a solid  complex, Cx^y,  of  variable  composition,  high  in  sulphur 
and  low  in  carbon  but  in  which  the  ratio  of  carbon  to  sulphur  is 
not  necessarily  constant,  and  which  is  stable  at  ordinary  temper- 
atures, As  there  was  less  of  the  oxygen  present  at  the  high  tem- 
peratures we  should  exi)eot  to  find  lov/er  percentages  of  sulphur 
adsorbed  at  the  higher  temperatures,  which  has  been  amply  verified 
in  previous  investigations.  17.H.  Adolph^^  studying  the  surface 
compounds  of  sulphur  and  nitrogen  comes  to  this  same  conclusion. 

He  studied  the  interior  and  exterior  of  lumps  of  coal  and  coke 
and  found  a distinct  excess  of  sulphur  in  the  surfetse  layer. 


-18- 


PART  III 
PXPERB^IEITTAL 

A. 

The  furnace  emploiT-ed  in  tide  investigi-tion  was  that  used 
oy  Dr.  M.J.  Bradley  in  this  laboratory  in  his  study  of  the  decom- 
position products  of  coal  carbonization^'^.  It  was  made  by  taking 
a six  foot  length  of  four  inch,  Ho.  18  Byer’s  pipe,  thr^ing  on 
flanges  and  thermocouple  pockets  and  having  these  joints  acetylene 
v/elded  to  insure  having  no  leaks  under  high  temperature  conditions. 
The  caps  extend-  one  and  one  half  inches  into  the  furnace.  The 
pipe  was  thinly  coated  on  the  outside  with  alundum  cement,  v/ound 
in  five  sections,  each  having  36i  feet  of  Ho.  14  A chromel  resis- 
tance wire,  and  again  coated  with  cement.  It  was  surrounded  by  a 
wooden  box  twenty  inches  square,  and  as  long  as  the  furnace,  and 
containing  pulverized  asbestos  and  sil-o— cel  insulation.  Bach 
heating  element  when  connected  directly  across  the  110  volt  line 
allowed  a maximum  current  of  20  amperes  to  pass  through, but  this 
could  be  reduced  to  five  amperes  by  means  of  an  external  slide 
wire  resistance  connected  in  series  at  the  switchboard.  3y  this 
means  the  heat  of  the  furnace  could  be  kept  constant  at  any  desir- 
ed temperature  be.tween  250®  and  900®0.  The  top  end  was  fitted 
with  a reservoir  and  feed  pipes  for  CSg,  superheated  steam, 

etc.,  and  also  with  a pressure  guage  and  reduced  pressure  guage. 

At  the  bottom  was  a safety  relief  valve,  or  constant  pressure 
valve  v/hich  could  be  adjusted  to  let  the  gases  escape  into  the 
line  leading  to  the  wet-gas  meter  at  any  desired 
pressure.  The  temperature  was  measured  by  means  of  a thermo- 
couple made  from  six  feet  of  Ho.  8 chromel  and  alumel  wire. 


-19- 


The  cold  juotion  was  kept  at  zero  ky  means  of  a thermos  bottle 
filled  with  ice  water  and  the  e.m.f.  was  read  on  a millivoltmeter 
which  had  been  standardized  at  known  temperatures.  This  gaYe 
readings  accurate  within  four  or  five  degrees.  The  interior  of 
the  furnace  was  also  lined  with  alundum  cement  to  prevent  corro- 
sion by  the  sulphur  compounds. 

3. 

The  CSg  was  piaced  in  a reservoir  above  the  upper  end  of 
the  furnace  and  by  means  of  a regulating  valve  passed  through  a 
sight  glass  into  the  furnace.  Eere  also  could  be  introduced 
gases,  as  hydrogen,  and  HgS  from  cylinders  or  generators,  or 
steam  from  the  high  pressure  line,  through  the  gas  fired  super- 
heater tubeo  Charcoal  could  also  be  heated  to  incandescence  in 
this  tube,  forming  water  gas  from  the  steam  passed  over  it.  In 
passing  down  through  the  furnace,  the  vapors  came  into  contact 
v/ith  the  various  carbon  forms  used.  Two  water  cooled  condensers 
collected  any  condensates  in  bottles,  vliile  the  gases  passed  on 
through  meters  and  were  burned.  At  the  completion  of  the  runs 
the  current  was  shut  off  from  the  switchboards,  and  the  furnace 
allowed  to  cool  down  to  about  150°C  before  opening. 

j • 

Gas  samples  v/ere  taken  in  two  liter  aspirator  bottles  in 
which  the  v;ater  had  become  saturated  v;ith  the  gases  in  question. 
These  were  analyzed  in  the  usual  manner  in  a modified  Orsat  appa- 
ratus. The  I/rehschmidt  method  of  analyzing  for  sulphur  content 
was  found  to  be  unsatisfactory  in  the  work,  owing  to  the  small 
and  variable  amounts  of  gas  coming  through  the  furnace  being  in- 
sufficient to  support  a st ea4y  flame  under  a trumpet  tube.  Eor 


mm 


-20- 


the  H^S  determinations  a Tutweiler's  burette  with  a standard 
iodine  solution  of  Icc  equal  to  one  grain  of  sulphur  per  100 
cubic  feet  was  found  to  be  sufficiently  accurate  for  the  major- 
ity of  determinations  in  which  the  percentage  of  ITgS  was  not  too 
great.  Two  determinations  w'ere  made  on  each  type  of  carbonace- 
ous substance  taken  from  the  furnace,  one  by  shaving  off  the  out- 
er one  sixteenth  inch  of  the  coke  or  charcoal  and  the  other  from 
as  near  the  center  of  the  lump  or  stick  as  possible.  These  were 
pulverized  in  a porcelain  mortar  to  60  mesh  and  dried  in  an  oven 
at  120°C  for  two  hours,  peroxide  fusions  were  then  made,  and 
the  sulphate  precipitated  from  an  acid  solution  by  10^  Bacig  in 
the  usual  manner.  This  precipitate , after  digesting  on  the  steam 
bath  for  at  least  three  hours,  in  no  case  presented  difficulty 
in  filtration  with  ordinary  A.D.L.  filter  paper.  The  precipita- 
tes v/ere  washed  twice  by  decantation  with  v;ater,  containing  a 
little  ECl  to  insure  the  removal  of  the  last  traces  of  iron  and 
then  transferred  to  the  filter  papers  and  washed  with  hot  distil- 
led v/ater  until  tests  with  a silver  nitrate  solution  showed  all 
the  chlorides  to  have  been  removed.  The  filter  papers  were  dried 
in  an  oven  and  ignited  carefully  in  porcelain  crucibles  and  the 
BaS04  calculated  to  percent  of  sulphur  in  the  air  dried  sample. 

The  best  fusions  were  obtained  with  a charge  of  O.Sgrems  of  coke 
or  charcoal,  0.75  grams  of  EGlOg,  one  scoopful  of  Ea202,(14  grams), 
and  about  1.0  gram  of  sugar. 

P. 

To  determine  the  area  of  the  furnace  in  which  the  greatest 
reactions  would  take  place,  sample  bundles  of  chercoal  were  placed 
in  the  furnace,  one  at  the  top,  and  one  at  the  center,  and  the 


last  near  the  lower  end  of  the  furnace,  and  passed  through 
with  the  furnace  at  a temperature  of  £00°C.  Analysis  showed  that 
the  charcoal  at  the  center  of  the  furnace  and  the  lower  end  ac- 
cumulated 0.60^  sulphur,  ?/hile  that  at  the  upper  end  only 
It  v»ras  decided  to  place  all  succeeding  charges  as  near  the  center 
as  possiole. 

In  order  to  determine  the  effects  of  the  temperature  of 
air  drying  and  the  physical  form  of  the  substance  on  the  sulphur 
content  of  the  impregnated  carbon  materials  during  this  part  of 
the  sample  preparation,  a sample  stick  of  charcoal  was  placed  in 
the  drying  oven  and  heated  for  two  hours  at  120 ®C.  An  exterior 
and  interior  sample  showed  9o04f.  and  9ol6f^  sulphiir,  respectively. 
Another  stick  of  the  seme  run  was  first  sampled,  pulverized,  and 
then  placed  in  the  oven  end  air  dryed  as  before.  This  gave  analy- 
ses of  6.92^  and  &.6lfo  for  the  exterior  and  interior  samples  re- 
spectively. It  was  accordingly  decided  to  be  necessary  to  first 
sample  and  pulverize  the  coke  or  charcoal  before  air  drying,  A 
third  stick  of  charcoal,  dried  in  this  manner,  was  found  to  con- 
tain 10.725^  sulphur  on  the  exterior  and  7.25f^  on  the  interior. 

Fach  sample  was  then  returned  to  the  oven  and  further  air  dried, 
with  frequent  stirring,  for  ten  hours,  after  which  they  analyzed 
6.34f  and  4. 56^, respectively.  Apparently  some  had  merely  been 
absorbed  and  was  driven  out  by  the  continued  heating.  It  was  de- 
cided that  the  loss  was  not  relatively  large  enough  to  warrant 
^^ytng  for  such  a long  period  of  time  and  the  two  hour  period  was 
chosen  for  the  standard  for  preparing  the  remaining  samples. 
Analyses  ?/ere  also  made  for  the  various  carbon  substances  used, 
and  are  shown  in  the  following  tables: 


c 

Substance 

S Exterior 

S Interior 

f Fe 

Metallurgical  coke 

1.08 

0.97 

1.47 

Low  Temperature  coke 

1.07 

1.05 

neglegible 

Petroleum  coke 

1.23 

1.18 

trace 

Wood  charcoal 

0.09 

0.09 

0 

The  metcllurgiGal  and  low  temperature  were  hoth  fair 
grades  of  coke,  hard,  and  rather  non-porous.  The  oil  or  petro- 
leum coke  was  obtained  from  the  crude  oil  stills  of  the  Standard 
Oil  Company  of  Whiting , Indiana.  It  was  of  a very  uniform  com- 
position, very  porous,  and  had  8 marked  jet  black  iridescence. 

The  charcoal  was  of  a good  grade  of  finely  grained  oak  charcoal 
with  a final  carbonization  temperature  of  about  550°  to  600 °C. 

T?* 

• • 

In  this  first  series  of  runs,  about  750  cc  of  CSg  per  kilo- 
gram of  crude  carbon  was  vaporized  and  passed  through  the  furnace 
at  various  temperatures  for  from  6 to  8 hours.  Several  referen- 
ces in  the  literature  show  that  the  coke  and  charcoal  are  being 
used  commercially  in  the  purification  and  removal  of  OSg  from  gas 
and  it  was  to  obtain  more  information  about  the  action  of  CSg 

on  crude  carbon,  that  this  part  of  the  work  ?^was  undertaken. 

46 

W.E.  Fulweiler  makes  the  statement,'^  it  seems  to  me 
that  the  man  who  is  trying  to  make  sulphur-free  gas  should  study 
the  organic  sulphur  compounds,  which  seem  to  vary  in  percentage 
_rom  three  to  possibljr  nine  or  ten.  They  are  the  compounds  that 
are  going  to  be  difficult  to  remove  by  any  method  that  we  know 
at  the  present  time,  and  if  we  are  going  to  make  a really  sulphur- 
free  gas  they  will  have  ^ be  solved".  After  the  normal  gas 
purification  it  may  still  contain  8 to  43  grains  of  sulphur  per 


I 


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-23- 


leo  cutic  feet'^’^.  J.  Matwin^®  descrilDes  experiments  in  which  one 
kilogram  of  wood  charcoal  lowered  the  sulphur  content?  of  one 
cubic  meter  of  gas  from  100  to  29.9  grains  per  100  cubic  meters. 

The  charcoal  was  regenerated  by  immersion  in  water  for  one  hour 
and  subsequent  drying  at  150°C.  The  removal  effect  of  v/ater  has 
been  known  for  some  time  in  the  case  of  nitrogen  and  hydrogen  sd- 
■ sorption  by  charcoal'^^.  H.  l^anner  found  that  one  kilogram  of 
charcoal  purified  E-G  cubic  meters  of  gas,  containing  73.1  grains 
of  sulphur,  to  20 oO  grains  per  100  cubic  feet,  A recent  British 
patent^^  covers  the  purification  of  gases  of  sulphur  after  the 
usual  Tf^S  removal  by  their  passage  over  finely  porous  carbon  or 
charcoal. 

The  following  tables  show  the  amounts  of  sulphur  found  on 
the  surface,  also  in  the  middle  region  of  chunks  of  carbon  substan- 
ces, after  having  been  treated  with  the  CSg  &t  the  temperatures 
noted. 

Substance.  Temp.  ITo.  ^Mineral  S.  f Final  S.^  Increase  in  S. 


Fxter . 

Inter 

.Fxt.‘ 

Int . 

Fxterior 

Interior 

Charcoal  410 °C 

(1) 

0.09 

0.09 

6.93 

6.61 

6.84 

6.52 

Charcoal  500°C 

fi) 

0.09 

0.09 

11.07 

9.29 

10.96 

9.20 

Charcoal  500®C 

f2) 

*0.09 

0.09 

10.74 

7.2E 

10.65 

7.16 

Charcoal  695°C 

(1) 

0.09 

0.09 

10.  IE 

10.52 

10.06 

9.43 

Charcoal  E9E°C 

(2) 

0.09 

0.09 

9.82 

9.45 

9.73 

9.36 

Charcoal  700°C 

fl) 

0.60 

0.16 

2.97 

2.92 

2.37 

2.76 

Metallurgical 

Coke  398®C 

fl) 

1.08 

0.97 

1.56 

1.55 

0.48 

0.58 

Metallurgical 

Coke  39E°C 

(2) 

1.08 

0.97 

1.30 

1.01 

0.22 

0.04 

low  Temperature 

Coke  400°C 

il) 

1.07 

l.OE 

1.16 

0.89 

0.09 

- 0.16 

Metallurgical 

Coke  E00°c 

(1) 

1.08 

0.097 

1.64 

1.08 

0.56 

0.11 

Metallurgical 

Coke  500  C 

fl) 

1.43 

1.28 

1.68 

1.48 

0.25 

0.20 

Metallurgical 

Coke  600°C 

(1) 

1.08 

0.97 

1.27 

1.19 

0.19 

0.22 

Metallurgical 

1 -Hfl 

0.97 

1 .lA 

r.,nn 

n.i 

-24- 


substance  Temp.  Ho.  f;  Miners!  S.  Final  B.  ^ Increase  in  S. 

Fxter.  Inter .Fxter.  Inter.  Fxter.  Inter. 

Metallurgical 

Coke  700®C  fl)  l.OC  0.84  1.20  1.21  0.20  0.47 

CTI  ~C6ke 70'0'^"TI1  1723  1718  ITU  Z.Th  0 .TB  1740 

^ A second  series  of  results  for  any  given  temperature  are  for 
an  entirely  new  sample  and  not  a duplicate  analysis  of  the  preced- 
ing sample. 

In  most  cases  about  80^  of  the  CSg  Vv^ss  recovered  in  the  conden- 
sate. The  gases  passing  to  the  meter  contained  frDm40  to  of 
CSg,  4.6  to  6.7f^  of  CO2.  1»37  to  2.0^-  unsaturated  and  2.2  to  2.7f^ 
of  saturated  hydrocarbons,  4.7  to  11. 8^^  of  Hg,  14.1  to  32.4^i  of  CO, 
and  1.5  to  4.55!  of  oxygen,  with  a very  little  methane,  ethane,  and 
benzene.  In  each  case  the  furnace  was  swept  out  thoroughly  with 
city  gas  befor  making  the  runs  but  considerable  oxj^gen,  hydrogen, 
etc.,  must  have  been  retained  by  the  charcoal,  and  coke,  to  give 
such  high  percentages  of  oxygen  and  hydrogen,  and  their  compounds, 
in  the  gas  analyses. 

The  most  outstanding  featiire  of  these  results  is  the  far 
greater  percentage  of  sulphur  found  in  the  charcoal  as  compared 
to  that  in  the  coke.  The  former,  being  of  an  extremely  porous 
nature,  besides  presenting  an  enorcious  surface,  with  a correspond- 
ingly hi^h  absorptive  capacity,  also  offers  the  opportunity  for 
capillary  action.  Lowry  end  Fulett  have  calculated  the  surface 
of  charcoal  to  vary  from  160  to  436  square  meters  per  gram.  With 
a material  of  this  kind  it  is  really  meaningless  to  talk  about  the 
surface  on  which  the  adsorption  can  take  piece.  Langmuir^®  states 
that  charcoal  probably  consists  of  atoms  combined  together  in  branch 
ing  chains  of  great  complexity.  Between  the  atoms  of  carbon  there 
must  be  spaces  of  all  possible  sizes  and  shapes.  There  would  be. 


-25- 


however,  a fairly  sharp  limit  to  the  number  of  molecules  which 
could  come  into  intimate  contact  with  the  carton  atoms,  the  limit 
corresponding  to  the  saturated  state  observable  in  adsorption  even 
by  porous  bodies. 

It  is  seen  that  with  both  charcoal  and  coke,  (except  the 
oil  coke) , a temperature  of  500°C  gives  the  highest  sulphur  con- 
tent, It  is  necessary  to  assume  in  all  of  our  experiments  that  an 
equilibrium  exists  between  the  incandescent  carbon  and  the  dissoc- 
iated vapors  employed.  Thus  ?/ith  we  will  have  the  equations: 

CSg  t heat  ^ C 4*  2s 

2S  + C (coke  or  charcoal)  — C^S^( surface  com- 

^ p ound ) 

IVe  might  assume  that  the  atomic  sulphur  produced  by  the 
dissociation  of  CS„,  in  contact  Vvith  the  incandescent  carbon, 
forms  the  carbon- sulphur  surface  compound,  2Iow  it  has  already  been 
sta.ted  that  t he  previous  work  on  this  theory  indicates  that  the 
formation  of  the  surface  compounds  is  impaired  at  the  higher  tem- 
peratures, At  the  same  time  CSg  is  not  known  to  dissociate  at 
reasonably  low  temperatures.  There  must,  hov:ever,  be  a certain 
temperature  at  which  the  two  effects  allow  a maximum  retention  of 
sulphur,  in  this  case  500^0* 

In  general  a distinct  excess  of  sulphur  is  found  in  the  sur- 
face samples,  which  is  what  we  v/ould  expect.  In  the  case  of  the 
coke  particularly,  however,  its  hard,  and  non-porous  nature  must 
be  considered  as  making  an  easy  and  thorough  penetration  of  the 
CSg  vapors  to  the  center  of  the  coke  lumps  a difficult  and  rather 
lengthy  process.  This  probably  accounts  for  the  fact  that  the 
maximum  percentage  sulphur  increase  in  the  interior  samples  re- 
quires a higher  temperature  than  that  in  the  case  of  the  maximum 
surface  increase* 


-26- 

F. 

In  the  ordin&ry  coking  process  there  exists  a considerable 
zone  of  temperature  wherein  the  decomposition  yieldsfixed  gases 

QO 

practically  free  from  sulphur  . As  has  been  previously  stated, 
HgS  is  expelled  during  the  coking  process  and  must  of  necessity 
pass  throughthe  incandescent  mass.  What  then  becomes  of  it  dur- 
ing the  period  of  minimum  sulphurgas  production?  hoes  the  H2S 
also  form  some  organic  sulphur  compound  with  the  carbon?  It  was 
with  a view  toward  answering  these  questions  that  the  reactions 
of  KgS  on  the  various  forms  of  carbon  were  studied. 

Fussell^®  studied  these  reactions  quite  extensively  and 
found  from  his  experiments  with  sugar  carbon  and  EgS: 

(1)  A determinati%^i7 Volume  che'^nge  of  FgS  could  not  be 
made  applicable  to  this  study. 

(2)  A time-saturation  study  showed  that  only  a very 
little  additional  sulphur  is  taken  up  after  the  first  hour. 

(3)  The  activity  of  the  carbon  toward  the  H2S  increases 
up  to  a temperature  of  about  770^0  and  then  after  this  there  is 

a decrease  in  the  amount  of  sulphur  combined.  Ee  explained  these 
results  on  the  basis  of  the  assumption  that  above  7C0°C  the  Eg 
formed  by  the  dissociation  of  E^S  has  a greater  tendency  to  re- 
move the  sulphur  than  the  carbon  has  to  hold  it. 

In  the  writer's  work,  HgS  generated  in  a Kipp  generator, 
and  collected  in  large  carboys  over  water,  giving  a constant  de- 
livery to  the  furnace,  was  employed.  At  first  it  was  mixed  with 
the  illuminating  gas  before  entering  the  furnace,  in  order  to  in- 
sure a constant  movement  of  the  over  the  incandescent  carbon. 
This  was  found  to  be  impracticable  hov/ever,  owing  to  the  difficult 


■:m6f^  ur’9fif\  , 


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-27- 


of  regulating  the  pressure  and  of  determining  the  amount  of  HgS 
being  used.  The  collection  of  the  H S over  v/ater  was  also  found 
unsatisfactory,  hut  much  more  succeseful  than  hy  attaching  the 
T'ipp  generator  direct  to  the  furnace.  The  HgS  was  slowly  passed 
through  the  furnace  until  gas  analysis  indicated  that  the  carbon- 
aceous material  was  saturated. 

The  results  of  these  experiments  follov/: 


Substence 

Temp  • 

f.  Initial  S.  ' 

^ Final  3. 

Increase  in  S, 

Exter.  Inter. 

Fxter. 

Inter. 

Fxter.  Inter. 

Charcoal 

580°C 

1.23  1.18 

1.27 

0.60 

0.04  -0.58 

Charcoal 

505°C 

0.09  0.09 

0.60 

0.16 

0.51  0.07 

Charcoal 

680°C 

0.09  0.09 

2.89 

1.64 

2.80  1.55 

Met.  Coke 

380°C 

1.08  0.97 

1.10 

0.76 

0.02  -0.21 

Oil  Coke. 

280°C 

1.2S  Xol6 

1.53 

1.57 

0.30  0.39 

Met.  Coke 

505°C 

1.08  0.97 

0.90 

0.81  - 

-0.18  -0.16 

Mete  Coke 

675°C 

0.90  0.81 

1.02 

1.73 

0.12  0.92 

Met.  Coke 

680°C 

1.08  0.97 

1.22 

1.27 

0.14  0.30 

Oil  Coke 

680°C 

1.23  1.18 

2.89 

1.64 

1.66  0.46 

At 

lower 

temperatures  the  gas 

issuing 

from  the  furnace  was 

so  high  in 

F2S  ■ 

that  the  use  of 

the  Tutweiler 

burette  was  imp os sib 

On  the  run 

at  380^0  an  Orsat  analysis 

gave  Kg 

S + OOg,  71. If;  Og, 

unsaturated  hydrocarbons. 

n • 

U . 

Hg,  V.9 

f;  ana  00,  0.7f.  At 

6C5°C  the 

results  v/ere  practically  identical. 

At  the  start  of  the 

run  at 

gases  came through  the  furnace  unchanged,  but 

soon  an  analysis 

showed  and 

C02, 

11.9^;  0 

£,  2.5<;  Hg,  B7.4f; 

and  CO,  25 

.8f . 1 

On  the  run  at  680 °C  hardly  a 

trace  of  KgS  appeared 

in  the  outcoming 

gases  and  the 

orsat 

analysis 

showed  FgS  and  COg , 

0£, 

3.2<; 

Fn,  77. and 

CO,  3 

.7^. 

These  results  show,  as  did  Russell’s  that  the  greatest  in- 


-28- 


oreese  in  percentege  sulphur  occurs  st  the  higher  temperatures. 

In  general  also,  v/ith  the  exception  of  some  of  the  results  on  the 
metallurgical  coke,  the  exterior  shows  a higher  percentage  sul- 
phur than  the  interior  samples.  A peculiar  result  is  to  he 
• noted  in  the  run  at  380*^0.  The  interior  of  the  charcoal  and 
metallurgical  coke  apparently  lost  some  of  its  sulphur  with  an 
increase  in  that  in  the  oil  coke,  particularly  in  the  interior. 

Ho  plausible  explanation  suggests  itself  to  the  writer  for  this. 
That  a true  equilibrium  must  exist  in  this  series  of  experiments 
is  noticeably  brought  out  in  the  run  at  505°0.  Both  charcoal, 
with  an  extremely  low  percentage  of  sulphur,  and  metallurgical 
coke  of  medium  content,  were  heated  in  the  furnace  together  and 
exposed  to  the  action  of  HgS  . The  charcoal  increased  in  the 
percentage  of  sulphur  but  apparently  at  the  expense  of  the  sul- 
phur contained  in  the  coke.  Thus  the  carbon-  sulphur  combination 
of  the  coke  must  possess  a vapor  tension,  or  itself  dissociate 
somewhat  at  this  temperature,  the  resulting  atomic  sulphur  act- 
ing on  the  carbon  of  the  charcoal  to  reform  the  combination. 

For  an  explanation  of  the  much  higher  temperature  necessary 
to|pr educe  s maximum  increase  in  sulphur  content  we  may  turn  to 

the  literature  on  the  studies  of  the  dissociation  of  FoS. 

*52 

Freuner*"  gives  the  following  data  for  the  percentage  dissocia- 
tion at  various  temperatures;  2,Zfj  at  627°C,  16.4'^j  at  947°0, 

31.7^  at  1137'^C,  and  76*lf^  at  1727®C.  There  would  thus  be 

little  atomic  sulphur  available  to  combine  with  the  car- 

Don,  even  at  680  Alscj  as  experiments  already  referred  to,  and 
the  results  of  the  next  series  of  ours  shows,  hydrogen  at  this 
temperature  causes  a very  great  removal  of  the  sulphur  combin- 


-E9- 


ation,  especially  from  charcoal.  Thus  we  may  account  for  the 
small  increases  in  sulphur  content,  even  in  the  charcoal,  in  the 
interaction  with  the  H^S  and  carbon. 

Though  the  ^£3  evolved  during  the  coking  period  is  exceed- 
ingly smaller  in  amount  than  that  employed  in  the  above  experi- 
ments, its  reaction  should  be  of  the  same  general  type  as  those 
just  described.  They  have  already  been  found  of  practical  appli- 
cation to  gas  purification  and  may  prove  of  greater  value  on  fur- 

53 

ther  study.  T7.F.  Lamoreaux  and  C.W.  Eenv/ick  give  a process  of 
removal  of  sulphur  from  furnace  gases  by  passing  through  hot  coke 
at  a temperature  maintained  above  1000°C  by  passing  an  electric 
current  through  the  coke.  A.  Engelhardt*"^  has  patented  a method 
to  remove  from  gases  by  the  use  of  activated  charcoal. 

C-. 

Many  references  have  previously  been  made  to  the  high 
percentage  of  sulphur  removed  by  hydrogen,  particularly  at  tem- 
peratures above  500*^0.  The  hydrogen  used  in  this  series  of  runs 


was  deliverrd  directly  into  the  furnace  from  cylinders.  The 
results  are  given  in  the  following  table; 


Substance 

Temp. 

Mo. 

^ Initial  B. 

^ Final 

S. 

Pecrea 

se  in  S 

Exter . 

Inter. 

Exter. 

Inter . 

Exter. 

Inter. 

Charcoal 

530°C 

(1) 

11.07 

9.29 

2.54 

2 .36 

76.1 

74.6 

Charcoal 

530  °C 

(2) 

10.74 

7.25 

2.51 

2.24 

76.6 

69.1 

Charcoal 

600°C 

(1^ 

10.95 

8.27 

1.66 

1.9S 

84.5 

76.0 

Charcoal 

600°G 

(2) 

8.71 

7.90 

2.83 

3.29 

56.0 

41 . 6 

Met.  coke 

(1) 

1 . 58 

1 . 48 

O' ."8  8 

"0TM3~ 

Met.  Cokef 

ret)  520 

cJd) 

1.10 

1.05 

0.76 

0.70 

30.9 

33.3 

Low. T emp .Coke 600 °C 

(1) 

1.16 

0.89 

1.12 

0.97 

3.5 

13.4 

Lov/ . T emp . 0 

okeSOC'C 

f2) 

1.07 

1.05 

1.27 

0.50 

-0.20 

52.4 

The  percentage  decrease  in  sulphur  is  that  percentage 
which  the ^percentage  of  sulphur  reduced  is  of  the  total  percent- 
age originally  in  the  sample  before  treatment. 

The  first  run  was  continued  for  ten  hours  to  see  if  a 


-30- 


oomplete  rffmovcl  of  tlie  sulphur  might  be  made.  The  gases  leaving 
the  furnace  at  the  beginning  of  the  run  contained  1300  grains  of 
sulphur  per  100  cubic  feet.  At  the  end  of  15  minutes  it  had  de- 
creased to  1200,  and  ten  minutes  later  to  1130.  This  rate  of  de- 
crees continued  somewhat  constantly  until  at  the  end  of  six  hours 
it  contained  but  150  grains  per  100  cubic  feet,  and  an  hour  later 
this  was  120  grains.  Fowever,  even  at  the  end  of  10  hours,  the 
gas  still  gave  a heavy  precipitate  v/ith  CdOlp.  This  would  seem 
to  indicate  that  a complete  elimination  of  sulphur  could  not  be 
produced  even  after  a long  period  of  gaseous  washing,  making 
such  a process  commercially  impracticable.  The  remainder  of  the 
gas  in  each  case  was  practically  pure  hydrogen. 

The  percentage  decrease  compares  very  favoraToly  with  the  re- 
sults of  other  experimenters  . The  results  with  the  lew  temper- 
ature coke  v/ould  seem  to  indicate  that  the  sulphur  in  it  was  pre- 
sent in  it  in  a somewhat  different  state  of  combination  than  in 
the  metallurgical  coke,  and  charcoal.  To  explain  the  results  on 
the  basis  of  Langmuir’s  theory  it  is  necessary  to  assume  some  dis- 
sociation of  the  carbon- sulphur  compounds|and  removal  as  dis- 

placing the  equilibrium  of  the  carbon- sulphur  combination  towards 
its  decomposition. 

TT 

X ' • 

The  effect'  of  superheated  steam  for  sulphur  removal  was 
next  tried.  The  interaction  of  steam  with  the  hot  carbon  within 
the  furnace  should  produce  hydrogen  and  CO  and  bring  about  a high 
sulphur  removal.  This  was  found  to  cause  a rather  excessive  de- 
struction of  the  coke  and  charcoal,  however,  so  additional  runs 
were  made  in  v/hicli  charcoal  was  heated  to  incandescence  in  the  gas 


Iv  ■ • - • • 


-M-—  . . •-.••v  , ■■■;;'■  r 

•;  ':.jc  ' ' ■ ■'  y ■■'  w^'  ■ 

V ‘J  ''  f";:'.'  I’l: 

r*X.  -■ 

, T r »'  ■*^*  I ' ' * ' ^ 

■ j J 

f 4 f 'f'  ■_  .t;/ 

' ; I ■■  ■•'  ) ''i;.4.  ' '•  ! *- 


• 0 


i • 


-31- 


heated  prelieater  outside  the  furnace  and  the  stec-in  passed  slowly 
over  this  giving  the  v;ater  gos,  as  "before,  "but  not  at  the  expense 
of  the  carhon  substances  of  investigation.  The  results  of  these 
experiments  are  as  follov/s: 


5-ub  stance 

. T emp . 

Ho. 

fa  Initial  S. 

f.  Final  S.  i)ecre 

ase  in 

( ste 

Hxter . 

Inter. 

Hxter . 

Inter.  Ex;ter. 

Inter 

Charcoal 

425°C 

(1^ 

10.96 

8.27 

2.76 

2.70  74.6 

67.3 

Charcoal 

425^0 

(2) 

8.71 

7.90 

3.47 

4.18  60.0 

47.3 

Charcoal 

425°C 

(3) 

2.53 

2.30 

1.40 

1.70  44.2 

26.2 

Tilet.  Coke 

510°C 

fl] 

1.43 

1.28 

1.12 

0.93  21.7 

27.3 

(water  , 

psl~ 

Charcoal 

680°C 

(1) 

2.97 

2.92 

0.57 

0.43  80.7 

85.2 

I'et.  Coke 

680°C 

(1) 

1.20 

1.21 

0.80 

0.85  33.3 

29.9 

Oil  Coke 

680°C 

fl^ 

1.41 

2.58 

1.40 

1.21  0.7 

53.0 

Considerable 

V 

v/as  produced. 

particularly  in  the 

runs 

0 

using  water  gas.  In  the  one  at  680  C the  gas  showed  60  grains 
of  suphur  per  100  cubic  feet  at  the  end  of  the  second  hour,  and 
260  grains  at  the  end  of  the  fourth.  A gas  analysis  taken  be- 
tv/een  these  tv/o  times  gave  HgS  t 002,6.7^;0£,  0.8f;  Ho,  68.3'^; 
and  GO,  23. 

The  use  of  the  water  gas  gave  in  general  even  better  reducf- 
tion  than  did  hydrogen,  and  has  tie  added  advantage  of  low  cost 
and  ready  preparation.  The  higher  temperatures  produced  the 
maximum  sulphur  removal  and  the  samples  containing  the  highest 
original  percentage  of  sulphur  showed  the  highest  reduction. 

It  is  also  to  be  noticed  ths.t  in  a majority  of  the  determinations 
the  exterior  samples  of  the  treated  carbon  substances  shewed  a 
lower  percentage  of  sulphur  than  the  interior  samples  of  the 
same.  To  account  for  the  large  percentage  reduction  in  the 
interior  of  tl.e  oil  coke  both  in  these  runs  and  those  employing 
hydrogen,  v;hile  the  exterior  remained  practically  unchanged,  or 
as  in  the  ease  of  hydrogen  actually  added  0.2f  sulphur,  it 


; 


..  ) 


v/ould  appear  that  the  outside  of  the  coke  differs  from  the  inter- 
ior. It  may  he  that  the  latter  still  retains  some  of  the  crude 
oil  hydrocarbons  from  the  distillation  which  aid  the  sulphur  re- 
moval from  the  interior. 

Iwosdz^^  studied  the  reactions  in  water  £;ps  formation  and 
states  that  the  primary  reaction  is  expressed  by  the  equation, 

C f HgO  CO  Eg 

The  CO  further  reacts  with  the  excess  stesm,  tending  to  form  CO2 
and  more  hydrogen,  thus; 

CO  -h  ► COg  + Eg 

The  result  is  the  establishment  of  a "v/ater  gas  equilibrium”  for 

each  temperature  employed.  All  three  products  of  thi£^^®composi- 

tion  have  marked  reducing  effects  on  the  carbon- sulphur  compounds. 
29 

Chiles  wishes  to  assume  that  there  is  a formation  of  a carbon- 
hydrogen  surface  compound  v/hich  CO  might  displace  giving  nascent 
hydrogen,  which  in  turn  could  decompose  the  corresponding  amount 
of  the  carbon- sulphur  combination. 

I . 

To  further  study  the  remove!  of  these  carbon- sulphur  com- 
pounds of  coke  and  charcoal,  experiments  v;ere  made  with  x^’-lene 
and  ordinary  city  gas.  The  results  of  these  runs  are  given  in 
the  following  table: 


Substance.  Vapor.  Temp. 

< Initial  S. 

^ Final 

s.  5 

Pecrease  in  8. 

Exter . 

Inter 

• Bxter. 

Inter. 

Fxter . 

Inter. 

Charcoal  Xylene  460°C 

9.89 

9.89 

8.71 

7.90 

13.6 

21.0 

Charcoal  City  Cas450°C 

S.89 

1.64 

0.96 

1.02 

6608 

37.8 

ITet . Coke  City  Gas4509c 

1.22 

1.27 

0.90 

0.84 

26.4 

33.8 

Oil  Coke  City  (xas450°C 

2.89 

1.64 

1,68 

1,69 

41.7 

-0.05 

These  data  show  that  xylene  is  much  less  effective  thr-n  city 
gas,  and  that  the  latter  prodiices  a relatively  high  reduction 


X 


( 


u 


t 


even  at  as  low  a temperature  as  4£0°C.  The  removal  in  the  case  of 
the  xylene  was  probably  due  to  the  hydrogen  produced  by  its  decom- 
position, a gas  analysis  showing  7.5^?  to  be  present  at  the  temper- 
ature employed.  It  is  also  probable  that  this  is  the  constituent 
which  was  most  active  in  producing  the  effectiveness  of  the  ordin- 
ary city  gas. 


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P4BT  17 
sm:i^AEY 

1.  Wood  charcoal  is  much  more  active  than  metallurgical, 
low  temperature,  or  petroleum  coke  in  its  adsorption  of  sulphur 
from  CSg  and  H2S,  a.lso  in  the  subsequent  removal  of  sulphur  by 
gases. 

2.  The  most  effective  temperature  for  the  combins.tion  of 
sulphur  from  OS2  is  500^0.  A sulphur  content  of  0,09fj  in  char- 
coal was  increased  to  11.07  and  9.29f,  respectively,  in  exterior 
and  interior  samples  in  a determination  of  this  temperature.  Metal- 
lurgical coke  increased  from  1.08  and  0.97fj  to  1.64  and  1.08^. 

5.  The  sulphur  from  H23  is  best  taken  up  at  680°C,  the  per- 
centage sulphur  in  charcoal  increasing  from  0.09^^  to  2.89^  and 
1.64^,  and  in  metallurgical  coke  from  1.08  and  C.9'7fj  to  1.22^3  and 
1.27f^. 

4o  In  general  the  exterior  samples  from  these  experiments 
show  a higher  sulphur  percentage  than  the  interior  ones.  It  is 
quite  probable  that  if  the  reaction  be  continued  long  enough  the  two 
will  become  equal. 

5.  Hydrogen  is  a very  effective  agent  for  desulphurization, 
reducing  the  sulphur  content  of  charcoal  from  11.07  and  9.29f^  to 
2^54  and  2. 36f^, respectively  in  the  exterior  and  interior  samples. 
That  of  coke  is  reduced  from  1.68  and  1.48  to  0.88  and  0.83^. 

6.  Steam  causes  excessive  oxidation  of  carbonaceous  mater- 
ial. 

7.  Water  gas  is  the  most  effective  ageit  of  all,  reducing 
the  sulphur  content  of  charcoal  from  2.97  and  2.92f!  to  0.£7  and  0.43^ 
and  that  of  metallurgical  coke  from  1.20  and  1.21^to  0.81  and  0.8£«^. 


6.  Xylene  is  not  very  satisfactory  for  desulphurization. 

3.  Ordinary  city  gas  is  very  effective,  reducing  the  sul- 
phur content  of  charcoal  from  2.89  and  l,64fj  to  0.97  and  1.02f^, 
and  that  of  metallurgical  coke  from  1.2?  and  1.27^  to  0.90  and 
0.84f^ 

10.  After  treatment  by  gases  the  exterior  samples  of  the 
coke  and  charcoal  generelljr  contain  less  sulphur  than  the  interior 
samples.  They  would  probably  become  equal,  hov;ever,  if  the  treat- 
ment were  continued  for  a long  enough  period  of  time. 

11»  It  is  probably  impossible  to  entirely  eliminate  the  sul- 
phur from  hot  coke  by  means  of  gaseous  washing,  and  even  if  it 
v/ere  the  length  of  time  required  would  make  the  process  commercial- 
ly Impracticable, in  all  probability. 

12.  The  use  of  hot  carbon  to  remove  the  organic  sulphur  com- 
pounds from  gases  may  prove  of  commercial  importance,  but  is  pro- 
bably not  praotioal  for  the  removal  of  K„S. 

2 ^ . 

13.  The  decided  action  of  water  gas,  h^^drogen,  and  illuminat- 
ing gas  in  lowering  the  sulphur  content  of  coke  and  charcoal  in- 
dicates that  desulphurization  by  passage  of  such  gases  through  the 
coking  mass  may  prove  of  commercial  value. 

14*  In  general  the  distribution  of  the  sulphur  on  the  in- 
terior of  the  carbonaceous  material  on  treatment  with  OSg  and  EgS 
is  as  follows:  Below  400°C  the  sulipiiiir  shiifts  from  the  interior 

to  the  exterior;  tbove  this  temperature  up  to  675*^0  in  the  cf^se  of 
the  metallurgical  coke,  and  680°C  v;ith  the  charcoal,  the  sulphur  in- 
creases in  both  the  interior  and  the  exterior  but  a greater  percent- 
age in  the  latter.  Above  these  temperatures  the  sulphur  continues 
to  increase,  but  is  greater  in  the  interior  samples. 


-26- 
PAI^T  V 
BI3LI0GRAPFTY 

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5.  Trans.  A.I.M.S.  (1908),  29,  545 

6.  J.I.R.C.  (1920),  p 1077-81 

7.  Bull.  A.I.K.E.  (1919),  #152,  1817  I 1622 

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9o  Bull.  A.I.M.E.  (1919),  1779-89 

10.  J.  Iron  5-  St.  Inst.  (1905),  406-31 

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16.  Bull.  A.I.M.E.  (1916),  179 

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18.  Bull.  Ill,  Eng.  Fxp.  Sta.  ITniv.  of  111. 

19.  Reo.  Trav.  Chira.  (1919),  132-58 

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« t 


t ? 


• .J 


f 


-37- 


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and  Am. 

Chem . 

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2436 

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36o  Pec.  Trav.  Chim.  (1919),  159-62 

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J.A.C.S.  (1916),  2221-95;  (1917),  39,  1848-1906, 

2849;  (1918),  40,  1361-1403. 

41.  J.Soc.  Chem.  I.  (1905),  473 

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of  Surface  Compounds",  U.  of  I.  (1921) 


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Fin.  c’.  Met 

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Cas  Trorld 

(1919) , 70,  39 

X 


f t 


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48.  J.  Gas  bel.  (1909),  52,  602-4 

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